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Reaction.—A delicate test for ethyl alcohol is the iodoforw
reaction. Pour a few drops of alcohol into a test-tube and add
about 5 c.c. of a solution of iodine in potassium iodide, and then
dilute caustic soda solution until the iodine colour vanishes.
Shake up and warm very gently to about 60°. If no turbidity
or precipitate appears at once, set the test-tube aside for a
time. Yellow crystals of iodoform will ultimately deposit, which
have a peculiar odour, and a characteristic star shape when
viewed under the microscope. The same reaction is given with

FIG. 39.
other substances, such as acetone, aldehyde, &c., but not with
methyl alcohol.
Potassium Ethyl Sulphate, CsH6OtSO8.OK
Dabit Ann. Ckint. Phys. 1800, (i) 34, 300 ; Claesson, /. prakt.
Chem. 1879 (2) 19. 246.
70 grms. (87 c.c.) absolute alcohol.1
50    5,     (27 cc.) cone, sulphuric acid.
The alcohol is poured into a round flask (J litre) and the
•sulphuric acid is slowly added and well mixed by shaking. A
1 For the preparation of methyl potassium sulphate the same quantity of methyl
alcohol is used ; in other respects the two processes are identical. The yield is
45—50 grams.